The physiological role of platelet membrane neutral glycolipids and gangliosides will be investigated by the analysis of the effects of specific anti-glycolipid antibodies on platelet function. The consequences of increasing the content of specific platelet plasma membrane gangliosides by the incorporation of exogenously supplied gangliosides also will be investigated. The effects of these alterations and modifications of platelet membrane glycolipids will be assessed on platelet functions, e.g., adhesion to collagen, aggregation, the release reaction, as well as on serotonin and alpha adrenergic receptor binding in platelets. The synthesis of glycolipids in platelets will be investigated. Also, the effects of thrombin on glycolipids and ganglioside synthesis in platelets will be investigated. Platelets from patients with disorders in which there is a high probability of abnormal platelet membrane glycolipids, e.g., myeloproliferative disorders, type IIa hyperlipidemia, and the Bernard Soulier syndrome, will be investigated. Platelets from these individuals will be evaluated for abnormal ganglioside and neutral glycolipid composition and structure. The fatty acid, sphingosine, and carbohydrate components of these glycolipids will be analyzed by gas-liquid chromatography.